Field of the Invention
The present invention relates to an object information acquiring apparatus and a control method thereof.
Description of the Related Art
Vigorous research on optical imaging apparatuses where light is irradiated onto an object, such as an organism, from a light source that is a laser or the like, and where information in the object acquired based on the entered light is imaged, is progressing in medical fields. One optical imaging technique is photoacoustic imaging (PAI). In photoacoustic imaging, pulsed light generated in a light source is irradiated onto an object. Thereby an acoustic wave (typically, an ultrasound wave) is generated from a tissue of the object (light absorber) which absorbed the energy of the pulsed light which propagated and diffused in the object. The object information is imaged based on a signal which is detected as an acoustic wave by a probe or the like and is outputted. In other words, the photoacoustic imaging is a technique to analyze a signal received by a probe, that is, an acoustic wave generated when a measurement target segment absorbs light energy and expands instantaneously, and to image a difference of absorptivity of the light energy between such a measurement segment as a tumor and other tissue. By this analysis processing, an optical characteristic distribution in the object, particularly an initial sound pressure distribution, a light energy absorption density distribution, an absorption coefficient distribution or the like can be obtained. These distributions can be used for measuring a specific substance in an object, such as oxygen saturation in blood. In recent years, pre-clinical research to image the blood vessel images of small animals using this photoacoustic imaging and clinical research to apply this theory to the diagnosis of breast cancer are actively promoted (see “Photoacoustic imaging in biomedicine”, M. Xu, L. V. Wang, REVIEW OF SCIENTIFIC INSTRUMENT, 77, 041101, 2006).
Non Patent Literature 1: “Photoacoustic imaging in biomedicine”, M. Xu, L. V. Wang, REVIEW OF SCIENTIFIC INSTRUMENT, 77, 041101, 2006
Non Patent Literature 2: “Reconstructions in limited-view thermoacoustic tomography”, Y. Xu and L. V. Wang, Medical Physics, 31(4), 724, 2004